This invention relates, in a general aspect, to a method of producing food articles ready for consumption and having a prolonged shelf-life.
More particularly, the invention relates to a method of thermally stabilizing, cooking, and packaging food articles ready for consumption which are intended for preservation over extended periods and which include one or more non-pumpable ingredients and optionally one or more pumpable ingredients.
In the following description and throughout the appended claims, the expression "non-pumpable ingredient" will be used to indicate:
a solid edible product of any size substantially free from process liquid,
a mixture of a liquid and solid particles of an edible product with a liquid-to-solid ratio below 45% and with a particle size below 25 mm, and
mixtures comprising a liquid and a particulate solid product with a liquid-to-solid ratio above 45% and a particulate diameter above 25 mm.
As an example, a food article of the aforesaid type may comprise a cooked stuffed pasta product (tortellini, ravioli and the like), dressed with a sauce. Another example is a milk-based cream incorporating big fruit lumps, whole strawberries or the like shrub berries.
Hereinafter in this description and throughout the appended claims, food articles of this kind will be referred to as complex food articles.
In the industrial-scale production of packaged complex food articles ready for consumption and having a prolonged shelf-life, there is a so far unresolved technical problem which schematically comprises two basic aspects.
A first aspect is represented by the difficulty of subjecting the food article to an adequate thermal treatment of stabilization, sterilization and/or cooking. When the thermal treatment is carried out in an autoclave, the solid ingredients of the food article (i.e. the so-called particulate) which vary in size and weight, require fairly long processing times, in the region of 15 minutes, if proper heat penetration is to be achieved, whereas the liquid and semi-liquid ingredients require definitely shorter times (in the region of 5 minutes).
This difference in response to thermal treatment and the paramount importance of providing full sterilization (or sanitization or stabilisation) of the particulate, involve necessarily that the liquid ingredient undergoes an excessive thermal treatment with an inevitable downgrading of its peculiar organoleptic characteristics.
The use of such particular "heat sources" as microwave emitters or the like electromagnetic radiation generators (magnetrons) may reduce to some extent the relevance of the aforesaid technical problem, but fails to eliminate it completely, while it rather adds the difficulty of controlling and regulating such heat sources.
A second aspect of the technical problem mentioned above is represented by the presence of non-pumpable solid ingredients. In fact, owing to the unavailability of a continuous stream of the food article through the thermal treatment station, the treatment should be carried out discontinuously with a recognized consequent productivity decrease.